What is elephant toothpaste?
Elephant toothpaste is the foamy substance formed by rapid decomposition of hydrogen peroxide in the presence of household dish soap. This experiment is also known as the “marshmallow experiment” due to the fluffy foam it produces! Since it’s a simple experiment with easily obtainable ingredients, it’s a very popular class demonstration/party trick for kids.
The basic principle of the reaction is this: hydrogen peroxide (H2O2) decomposes over time, forming water and oxygen (H2O + O2) (if you’d like a refresher on decomposition reactions, click here!). Below is the full balanced reaction.
2H2O2 (aq) -> 2H2O (l) + O2 (g)
A catalyst speeds up this reaction. The oxygen combined with the dish soap is what creates the massive amounts of foam!
Elephant Toothpaste Ingredients
- 3% hydrogen peroxide
- Dish washing soap
- Catalyst- can be yeast solution (dry yeast in warm water), potassium permanganate (dissolved in a small amount of water), magnesium dioxide, or potassium iodide
- Container – could be a beaker, plastic bottle, graduated cylinder- whatever chemistry lab glassware you’d like to use!
- Food coloring (optional)
- A nice, easy-to-clean space
Elephant Toothpaste Recipe
- Pour ½ cup of peroxide into your ‘toothpaste’ container.
- Add a generous amount of dish soap.
- If you want to add color, now is the time. Add it directly to the peroxide for a solid color, or let it gently drip down the sides of the container to create stripes!
- Add your catalyst.
- Enjoy the bubbles!
What if I want a bigger foam-splosion?
You can achieve a more dramatic reaction in one of two ways. One- use more of your catalyst. This will speed up the reaction and cause oxygen to be released faster. Two- use a more concentrated peroxide. While 3% is the most readily commercially available peroxide, it is possible to get concentrations of up to 50%. When you use more concentrated peroxide, more oxygen will be released in the reaction. As a result, you’ll end up with a much more dynamic reaction!
However, exercise extreme caution if you choose to use highly concentrated peroxides! Hydrogen peroxide is extremely corrosive, and could cause serious burns if mishandled. If you’re conducting this experiment with a younger audience (or volunteer!) it might be better to stick with a safe 3%. If you do choose to use a more concentrated peroxide, it might be better to start with a smaller volume at first, and use less catalyst so the reaction proceeds at a controlled rate.
People who want a more dramatic reaction generally use 30% hydrogen peroxide. We don’t recommend using a higher percentage than that, and be sure to wear gloves.
Choosing a catalyst
Yeast will work as a catalyst, and it is safe and easily available. However, the reaction is not overly dramatic. The best choice is potassium iodide or sodium iodide, as it does not stain like manganese dioxide or potassium permanganate. Potassium iodide is also safer to use than potassium permanganate, which is a very strong oxidizing agent. Although safer, it is still recommended that you avoid contacting potassium iodide with the skin or eyes, as it is mildly toxic.
Can I touch the toothpaste?
In general, yes, but be cautious! When you use higher concentrations or an excessive amount of peroxide, it is possible to have some unreacted peroxide still in the foam, and this could cause serious burns. This reaction is also exothermic, meaning the flask will be hot to touch after the reaction takes place. Visit our safety notes page for more safety information.
That’s really all there is to it! If you’d like to see this experiment in action, click here to see the elephant toothpaste tips and tricks video on our channel. Good luck!